Suspension insulator having a pin provided with a shield sleeve



1963 E. c. RYAN ETA]. 3,076,868

SUSPENSION INSULATOR HAVING A PIN PROVIDED WITH A SHIELD SLEEVE Filed Aug. 8, 1960 INVENTORS EDMUND 6. RYAN BY :OHNKEAYLOR ATTORNEY United States Patent Office 3,076,868 SUSPENdllGN lNflULATGR HAVING A PlN PROVTDED WITH A Eilllllllbl) SLEEVE Edmund tC. Ryan, Mansfield, and .l'ohn J. Taylor, Medina,

()hio, assignors to The Ohio Brass Company, Mansfield,

Ohio, a corporation of New Jersey Filed Aug. 8, 1960, Ser. No. 43,232 13 Claims. (Cl. 174-132) This invention relates to insulators for power lines and particularly to suspension insulators for use individually, or in groups as series suspension strings.

Suspension insulators for electric power lines have been eveloped to a high degree, but certain problems have existed with regard to the long-term life of the insulator at locations wherein certain contaminants are present in the atmosphere. Particularly the atmospheric contaminants are deposited on the under side of the insulator adjacent the pin and cause the formation of oxidation cells, so called, and corrosive attack upon the pin. The corrosive action produces oxidation of the metal and ultimate destruction of the pin adjacent the body of cement utilized to secure the pin to the insulator body. More important, the growth of corrosion products at the boundary of the cement and pin causes an expansion of the cement and, ultimately, cracking of the ceramic insulating body. This problem has been successfully dealt with by the use of a shield sleeve which separates the shank of the pin from the cement and useful arrangements thereof are described in United States Patents 2,443,435 and 2,443,436, issued June 15, 1948, to J. J. Taylor. Extensive tests have demonstrated the feasibility and usefulnesss of the shield sleeve in reducing corrosion effects in installations in which the insulators are subject to the adverse effects of atmospheric contaminants.

In accordance with the present invention suspension insulators are provided in which a conical shield sleeve is utilized to protect the shank of the pin in the region adjacent the exposed portion of the cement body which secures the pin to the insulator. The interior end of the sleeve, i.e., the portion having the smaller diameter, surrounds and is attached to a shoulder formed as an integral part of the pin adjacent the head of the pin. The head is constituted with a spheroidal exterior surface for directing the forces exerted by the pin against the body of cement through the insulator wall to the skirt of the cap. The convergent relation of the sleeve and head results in a mutual disposition of those parts and of the insulator body and cement body such that a favorable distribution of the compressive forces exerted on the cement by the head of the pin is effected, while permitting small deformations of the ball of the pin without excessive strain or fatigue of the parts. Thus the insulator of the invention has improved strength, durability, and life, particularly under conditions of shock and/or severe transient overload.

The invention will be more fully understood by reference to the following detailed specification and claims taken in connection with the appended drawings, in which:

FIG. 1 is a side elevation view, partly in section and partly broken away, of a suspension insulator illustrating the invention;

FIG. 2 is a side elevation View of the suspension pin and sleeve of the insulator of FIG. 1, also partly in section;

FlG. 3 is a section view of the pin and sleeve of HQ. 2 taken along the line 3-3 of FIG. 2; and

FIG. 4 is a view of the pin and sleeve of FIG. 2, taken along the line 4 -4 in FIG. 2, as though the sleeve of FIG. 2 were modified as hereinafter described.

Referring now to FIG. 1, there is shown a suspension insulator it) comprising an insulator body ii, a. cap 12,

Patented li e ia 5, 19%

2 pin 13 and sleeve The insulator body if. is constituted of a vitreous electrical insulating material, usually porcelain, shaped as a disc 15, a central part or bell i6, and skirts on the under part of the disc 15. The cap 12 is secured to the exterior of the hell i by a body 17 of Portland cement and a coating 18 constituted by sand particles embedded in a layer of glaze which extends around the exterior of the bell 16. The pin 13 and sleeve 14 are held in the open interior of the bell 16 by a body 19 of Portland cement and a coating 29' constituted by particles of sand embedded in a layer of glaze which extends peripheraily about the interior of the bell. A pad 21 of felted paper extends across the top of the head 22 of the pin 13 and the exterior surface of the head 22 is covered with a coat of asphalt in order to permit a slight yielding of the pin with respect to the body 19 of cement under load, impact, or shock, as is hereinafter described.

The cap 12 is formed as a socket 23 at the outer end thereof and the pin 13 is formed as a ball 24 at the outer end thereof. The socket 23 receives the pin and ball of the next adjacent insulator to the insulator iii. The pin 13 and ball 24 are received in the cap socket of the next insulator below the insulator it to constitute a series string of suspension insulators. The socket 23 and ball 24 may, of course, be utilized to connect the insulator it to ancillary suspension and strain apparatus. Whatever the association of parts, the insulator i9 is loaded in tension, i.e., with a series connection between the parts.

Referring now to FIGS. 2, 3 and 4, the pin 13 is constituted by the head 22, the ball 24, shank 25 and shoulder 26. The pin 13 is constituted as a unitary forged or upset piece with the head 22, the ball 24- and the shoulder 26 constituted as an integral part of the pin. As shown, the head 22 may have an opening 27 although the entire head may be solid.

The head 22 has the exterior surface 28 thereof between the shoulder 26 and the top surface 29 formed as a spherical surface of revolution, that is with the center of curvature of the are which defines the surface offset with respect to the longitudinal axis of the pin, the radius of the are being greater than the greatest radial extent at the extremity of the head. This configuration is advantageous in that the direction of the compressive forces exerted upon the body of cement 19 are such that those forces are transmitted through the Wall of the bell 1e and are received by the lower extremity 31 of the cap 12. The spherical configuration referred to provides a desirable distribution of forces in the body 1) and the side wall of the bell in.

The term spheroidal as used in the claims refers to any surface having a circular outline in one direction and at least some form of circular symmetry in another direction. Thus the exterior surface 28 above, constituted as a surface of revolution about the longitudinal axis of the pin, is referred to as spheroidal as is a surface in the form of a zone of a sphere in which the center of curvt.- ture lies on the longitudinal axis of the pin. A particular spheroidal shape is not necessary and the surface may depart from a spherical contour to some extent.

The contour of the surface 28 has, however, an importaut relation to the shape and disposition of the sleeve 14. As is shown, the sleeve 14 has a generally conical configuration such that the smaller end of the sleeve is disposed adjacent the outward extremity of the head 22 by reason of its attachment to the shoulder 26. Accordingly, the shapes of the head 22 and the sleeve id are complementary in that the body of cement 19 has its greatest inward extent adjacent the shoulder 25 and the inward extremity of the sleeve 14.

The shape of the body of cement 19, with a decreasing radial thickness in proceeding outward from the juncture of the head 22 and the sleeve l4, effects a desirable disaovaeee s3) tribution of the load exerted by the head of the pin. Thus a principal part of the load is transmitted to the longitudinal wall of the bell 16 adjacent the head 22, or adjacent the head 22 and the inner extremity of the sleeve 14, whatever the condition of the pin, rather than being distributed along the wall of the bell and to the disc 15. Accordingly, the wall of the bell 16 is loaded primarily in the radial direction rather than in tension in the longitudinal direction and less susceptible to fracture under conditions of severe load.

Again, this organization of the sleeve 14 and shoulder 26 together with the sphericity of the surface 28 referred to the longitudinal axis of the pin 13 at the inward extremity of the shoulder 26 results in a significant reconnection or'bond between the sleeve or the pin is much less liable to part than would be the case if the sleeve was attached to the pin along a larger radius;

I Secondly, outward movement of the pin under load, due to the yielding of the surrounding body of cement outwardly of the ball 24 or due to elongation of the gain, permits a natural separation of the sleeve from the body of cement at or below the body of cement. Moreover a return to a tight fit along the body of cement is more likely to be achieved after unloading;

Third, the insulator is less susceptible to damage due to impact forces generated at the exposed end of the pin 13 by longitudinal blows, improper handling, dropping the insulator on the ball, or other abuse of the insulator, either singly or when connected in a series string. While the pad 21 tends to absorb a certain amount of the impact, the forces are transmitted primarily from the sleeve 14- against the body of cement 19 since the spheroidal surface 28 of the head 22 separates from the body of cement 19 under inward movement of the pin. The shock is thus absorbed in large part by yielding of the sleeve 14 somewhere along its length.

Again, since the spacing between the sleeve 14 and the shank 25 of the pin is greatest adjacent the outward part of the body of cement 19, the range of deformation of the sleeve is greatest in the region where the sleeve is most subject to pressure because of the growth of products of corrosion. Accordingly, the configuration perrnits the use of a heavier sleeve together with a larger body of cement, and a consequent greater increase in strength of pin support than would otherwise be the case.

The wall of the sleeve may preferably be formed along its outer extremity with longitudinally extending convolutions (shown in FIG. 4). The convolutions are of diminishing height in preceding toward the shoulder 26 so that the sleeve has an essentially smooth conical wall along the surface of contact with the shoulder 26. Such arrangement facilitates inward yielding of the sleeveas well as improving the fit between the sleeve and the body of cement because of elongation or other extensions of the pin under load.

The sleeve 14 is attached to the pin 13 by interengagement of the sleeve with the shoulder 26 and the head 22. The inside surface of the sleeve is tightly engaged with the outside surface of the shoulder 26 while the end of the sleeve abuts the head 22 to prevent movement of the sleeve away from the shoulder 26. The sleeve may be formed in place on the sleeve by extrusion or by swedging a blank onto the pin.

The sleeve 14 and the pin 13 are effectively united into 'a. single piece by galvanizing the entire pin and sleeve assembly, e.g., by dipping in a bath of molten zinc. The coated zinc forms a moisture-tight mechanical and protective bond between the sleeve and the pin along the co-extending lines and surfaces of the two parts and the sleeve and pin as well or a protective coating over the sleeve and pin. The extent of the penetration of the zinc between the sleeve 14 and the shoulder 26 along the contacting surfaces is dependent upon the fit between the inner surface of the sleeve and the conical surface of the shoulder. A tight fit and exact positioning of the sleeve on the pin with zinc coatingof the entire surface of the pin may be assured by galvanizing the pin before the sleeve is formed on the pin and then regalvanizing the entire assembly. The galvanized coating is, of course, desirable for protection of the pin and sleeve assembly against corrosive attack during use.

The pin 13 is preferably made of medium carbon or medium alloy steel. The sleeve 14 is preferably made of low carbon or low alloy steel, althoughthe material used is not particularly critical. Some of the considerations in the selection of materials is set forth in United States Patent No. 2,443,435 idem.

It is to be'understood that the foregoing description is not intended to restrict "the scope of the invention and that various rearrangements of the partsand modificationsof the design may be resorted to. The following claims are directed to combinations of elements which embody the invention orinven'tions of this application.

Weclaim: l. A suspension'insulatorcomprising an insulator body of vitreous insulating material constituted by a disc and "a bell extending outwardly from the disc on one side of "the disc and defining a pin opening on the remaining-side of the disc, arnetal cap received over the hell on the exterior thereof with the side wall of the cap extending along the longitudinal wall of the bell,-a body of cement between the bell and the cap securing the cap to the said body, a pin received in the interior of the said bell, the said pin being constituted by a shank, ahead at the inner extremity thereof, and a shoulder. adjacent the head, the head being tapered inward in the direction of the shoulder and having the exterior surface thereof disposed within the cap, a generally conical metal sleeve disposed coaxially about the pin and attached to the pin by a mechanical joint constituted by confinement of a smaller end of the sleeve between the shoulder and the head, the said sleeve having a smaller radius at the extremity thereof than portions of the said shoulderrand head aw-ay from the extremity of the sleeve, and a body of cement between the wall of the said bell, the head of the pin, and the sleeve for holding the pin and sleeve, and the said sleeve extending at the larger end thereof beyond the exposed surface of the cement.

2. The invention in accordance with claim 1 in which the sleeve has corrugated convolutions adjacent the outward extremity thereof.

3. The invention in accordance with claim 1' in' which the mechanical joint is constituted by engagement of the sleeve with a conical exterior surface of the shoulder and abutment of the sleeve on the head of the pin adjacent the smaller end of the shoulder.

4. The invention in accordance with claim 3, in which the sleeve is bonded to the pin by means of a metal coating over the adjacent portions of the sleeve and pin.

5. The invention in accordance with claim 1 in which the exterior surface of the head is coated with an asphaltic material to permit slight transverse deformations of the pin at the ball end thereof.

with claim 5 with the end of the head of vitreous insulating material constituted by a disc and a bell extending outwardly from the disc on one side of the disc and defining a pin opening on the remaining side of the disc, a metal cap received over the bell on the exterior thereof with the side Wall of the cap extending along the longitudinal wall of the bell, a body of cement between the bell and the cap for securing the cap to the body, a pin received in the interior of the said bell, the said pin being constituted by a shank, and a head at the inner extremity thereof having a generally spheroidal surface in the direction of the shank, a conlical metal sleeve surrounding the pin, the said sleeve having, at the smaller end thereof, substantially the same transverse dimension as the shank, less than the transverse dimension of the head, and having the larger end thereof spaced from the shank, and means attaching the sleeve to the pin adjacent the head at the smaller end of the sleeve, and a body of cement between the longitudinal wall of the bell, the head of the pin and the sleeve for holding the pin and the sleeve in the pin opening and distributing forces exerted by the pin from the head of the pin to the longitudinal wall of. the bell, said sleeve extending at the larger end thereof beyond the end of the [second named body of cement, and the radial extent of the head and of the larger end of the sleeve from the shank being substantially greater than that of the smaller end of the sleeve and that portion of the head adjacent the smaller end of the sleeve and the inward extent of the second named body of cement being greatest adjacent the smaller end of the sleeve between the sleeve and the head.

9. The invention in accordance with claim 8 in which the sleeve is attached to the pin by inter-engagement of the interior of the sleeve with a conical surface of a shoulder on the shank of the pin adjacent the head and abutment of the extremity of the sleeve on the head of the pin.

10. The invention in accordance with claim 8 in which the sleeve is bonded to the pin by means of a metal coating over the adjacent portions of the sleeve and pin.

11. In a terminal for a suspension insulator, an integral metal pin constituted by a shank, a head at one end of the shank and a shoulder on the shank adjacent the head and a metal sleeve surrounding the shank and spaced therefrom, the said sleeve having a conical extent along the greater part thereof adjacent the head and having the smaller end of the sleeve extending about the shank and attached thereto between the shoulder and the head.

12. In a terminal for a suspension insulator, an integral metal pin constituted by a shank, a head at one end of the shank and a shoulder on the shank adjacent the head, the head and the shoulder being tapered in ward in the mutual direction thereof, and a metal sleeve surrounding the shank and spaced therefrom, the said sleeve having a conical extent along the greater part thereof adjacent the head and having the smaller end of the sleeve extending about the shank between the shoulder and the head and attached thereto by engagement of the sleeve with a conical exterior surface of the shoulder and abutment of the smaller end of the sleeve against the head.

13. A terminal for a suspension insulator in accordance with claim 12 in which the sleeve is united with the pin by means of a metal coating extending over and about the adjacent portions of the sleeve and pin.

References Cited in the file of this patent UNITED STATES PATENTS 1,927,639 Gramss Sept. 19, 1933 1,994,293 Taylor Mar. 12, 1935 2,383,090 Torok Apr. 21, 1945 2,443,435 Taylor June 15, 1948 

1. A SUSPENSION INSULATOR COMPRISING AN INSULATOR BODY OF VITREOUS INSULATING MATERIAL CONSTITUTED BY A DISC AND A BELL EXTENDING OUTWARDLY FROM THE DISC ON ONE SIDE OF THE DISC AND DEFINING A PIN OPENING ON THE REMAINING SIDE OF THE DISC, A METAL CAP RECEIVED OVER THE BELL ON THE EXTERIOR THEREOF WITH THE SIDE WALL OF THE CAP EXTENDING ALONG THE LONGITUDINAL WALL OF THE BELL, A BODY OF CEMENT BETWEEN THE BELL AND THE CAP SECURING THE CAP TO THE SAID BODY, A PIN RECEIVED IN THE INTERIOR OF THE SAID BELL, THE SAID PIN BEING CONSTITUTED BY A SHANK, A HEAD AT THE INNER EXTREMITY THEREOF, AND A SHOULDER ADJACENT THE HEAD, THE HEAD BEING TAPERED INWARD IN THE DIRECTION OF THE SHOULDER AND HAVING THE EXTERIOR SURFACE THEREOF DISPOSED WITHIN THE CAP, A GENERALLY CONICAL METAL SLEEVE DISPOSED COAXIALLY ABOUT THE PIN AND ATTACHED TO THE PIN BY A MECHANICAL JOINT CONSTITUTED BY CONFINEMENT OF A SMALLER END OF THE SLEEVE BETWEEN THE SHOULDER AND THE HEAD, THE SAID SLEEVE HAVING A SMALLER RADIUS AT THE EXTREMITY THEREOF THAN PORTIONS OF THE SAID SHOULDER AND HEAD AWAY FROM THE EXTREMITY OF THE SLEEVE, AND A BODY OF CEMENT BETWEEN THE WALL OF THE SAID BELL, THE HEAD OF THE PIN, AND THE SLEEVE FOR HOLDING THE PIN AND SLEEVE, AND THE SAID SLEEVE EXTENDING AT THE LARGER END THEREOF BEYOND THE EXPOSED SURFACE OF THE CEMENT. 